Motorized vehicles include a powertrain operable to propel the vehicle and power the onboard vehicle electronics. The powertrain, or drivetrain, generally includes an engine that powers the final drive system through a multi-speed power transmission. Many vehicles are powered by a reciprocating-piston-type internal combustion engine (ICE). The internal combustion engine converts chemical energy stored in fuel (gasoline, diesel, bio fuels, natural gas, or other fuels) into kinetic energy through combustion of the fuel mixed with air.
Hybrid vehicles utilize multiple, alternative power sources to propel the vehicle, minimizing reliance on the engine for power. A hybrid electric vehicle (HEV), for example, incorporates both electrical energy and chemical energy, and converts the same into mechanical power to propel the vehicle and power the vehicle systems. The HEV generally employs one or more electric machines (motor/generators) that operate individually or in concert with the internal combustion engine to propel the vehicle. The electric machines convert kinetic energy into electrical energy which may be stored in an energy storage device. The electrical energy from the energy storage device may also be converted back into kinetic energy for propulsion of the vehicle.
In a diesel engine, combustion of an overly rich fuel mixture may result in the generation of a carbon-based smoke. This smoke generation often defines a torque-load limit (i.e., the smoke limit), above which the fuel cannot be completely combusted. While it is possible to obtain more additional engine torque by exceeding the smoke limit (as it is considerably lean of the stoichiometric ratio), the resultant combustion is highly inefficient and any extra power comes at the cost of reduced combustion efficiency, high fuel consumption, and exhaust smoke.